Resource Statement Disclosure: What JORC 2012 Actually Requires You to Write

I review a lot of resource reports. Not one of them has been fully compliant with JORC 2012 on the first pass. Not because the geologists don’t know the Code — most do — but because the disclosure requirements are specific, granular, and easy to overlook when you’re focused on the estimation itself.

The resource statement is the single page in your report that investors, regulators, and competitors will actually read. Getting it wrong isn’t a footnote issue. It’s the difference between a report that passes due diligence and one that gets sent back for revision.

This post covers exactly what JORC 2012 requires in your resource statement disclosure, with specific examples from Indonesian projects.

The mandatory elements

JORC 2012 Clause 25-27 specifies what a Public Report of Mineral Resources must contain. Here’s the checklist:

1. Tonnes and grade — with confidence categories

Your statement must report tonnes and grade for each confidence category separately:

Resource Statement — Project X (as of 1 July 2026)

Measured:    12.5 Mt at 1.85 g/t Au = 744,000 oz Au
Indicated:   28.3 Mt at 1.12 g/t Au = 1,019,000 oz Au
Inferred:    15.7 Mt at 0.87 g/t Au = 439,000 oz Au
Total:       56.5 Mt at 1.21 g/t Au = 2,202,000 oz Au

Common mistake: Rounding tonnes and grade to make the resource look bigger. If your model gives 12.47 Mt at 1.847 g/t, don’t round to 12.5 Mt at 1.85 g/t — the rounding adds 15,000 oz that isn’t there. Use the model numbers.

2. Cut-off grade — stated explicitly

“The Mineral Resource is reported above a cut-off grade of 0.5 g/t Au.”

That’s it. One sentence. But you’d be surprised how many reports bury this in an appendix or omit it entirely. Without the COG, the resource statement is meaningless — the reader has no way to judge whether the tonnage is optimistic or conservative.

For Indonesian deposits: If you use different COGs for different domains (oxide vs sulfide, open pit vs underground), state all of them:

The Mineral Resource is reported above:
- 0.3 g/t Au for oxide material (open pit, 85% recovery)
- 0.5 g/t Au for transitional material (open pit, 55% recovery)
- 0.8 g/t Au for sulfide material (underground, 45% recovery)

3. Metal equivalents — only if justified

If you report metal equivalents (e.g., AuEq for a Cu-Au deposit), JORC 2012 Clause 31 requires:

• The individual grade for each metal
• The metal prices used
• The recovery for each metal
• The formula

Most Indonesian polymetallic projects I’ve reviewed either skip the formula or use a single recovery for all metals. This is non-compliant.

4. “Reasonable prospects for eventual economic extraction”

JORC 2012 Clause 20 requires you to state the basis for believing the resource has reasonable prospects. This isn’t a vague statement — you need to reference:

• Mining method assumed (open pit, underground, both)
• Metallurgical recovery assumptions
• Cut-off grade basis
• Any modifying factors

Example wording:

The Mineral Resource has been assessed for reasonable prospects for eventual 
economic extraction using an open-pit mining method at a gold price of 
USD 1,750/oz, metallurgical recovery of 85% (oxide) and 55% (sulfide), 
total operating cost of USD 12.00/t, and a cut-off grade of 0.5 g/t Au. 
Pit shell optimization was conducted using Whittle software with a revenue 
factor of 0.7.

5. Competent Person statement

The information in this report that relates to Mineral Resources is based on 
information compiled by [Name], who is a Member of the [Australian Institute 
of Geoscientists / AusIMM] and has sufficient experience relevant to the 
style of mineralisation and type of deposit under consideration to qualify 
as a Competent Person as defined in the 2012 Edition of the JORC Code. 
[Name] consents to the inclusion in the report of the matters based on 
their information in the form and context in which it appears.

Common mistakes:

• Using “Competent Person” without naming the person
• Missing the membership affiliation (must be AusIMM or AIG)
• Missing the consent statement
• Using a CP who doesn’t have 5+ years of experience in that deposit type

6. Table 1 assessment

JORC 2012 requires that Table 1 — the checklist of assessment and reporting criteria — be included in the report or referenced as publicly available. Table 1 has three sections:

• Section 1: Sampling Techniques and Data — drilling methods, sampling, assay QA/QC
• Section 2: Reporting of Exploration Results — geological interpretation, dimensions, boundaries
• Section 3: Estimation and Reporting of Mineral Resources — estimation methodology, cut-off grade, mining factors

Most reports include Table 1 but fill it with boilerplate text. “Drilling was conducted to industry standard” is not a Table 1 answer. JORC expects specific, project-level detail.

What I see missing most often

A. Date of the resource estimate

“Effective date: 1 July 2026.”

One line. Missing from 60% of reports I review. Without it, the reader can’t tell if the resource is current or three years old.

B. Previous estimate comparison

JORC doesn’t strictly require this, but best practice is to show what changed since the last estimate:

The Mineral Resource estimate has been updated from the previous estimate 
dated 15 January 2026. Tonnage increased by 12% due to additional drilling 
in the North Zone. Grade decreased by 5% due to revised domaining of the 
oxide-sulfide boundary.

C. Statement of whether this is a new estimate or a re-statement

This is a new Mineral Resource estimate. No previous estimate has been 
reported under the JORC Code for this deposit.

Or:

This is an updated Mineral Resource estimate. The previous estimate was 
reported on 15 January 2026.

D. Material assumptions for Inferred Resources

JORC 2012 Clause 25 requires you to state whether Inferred Resources are modifying or not. Inferred is based on limited information — you need to say what assumptions you made to extrapolate.

Inferred Resources are based on drill spacing of 80m × 80m and extrapolation 
of geological interpretation beyond drill data by a maximum of 40m. Grade 
estimation used nearest-neighbor assignment with a search ellipse oriented 
parallel to the mineralized trend.

KCMI 2017 alignment

KCMI 2017 mirrors JORC 2012 in most disclosure requirements, with two additions:

1. Indonesian language version — the resource statement must be available in Bahasa Indonesia for Indonesian regulatory submissions
2. Registered Competent Person — for KCMI, the CP must be registered with the Indonesian Council of Geologists (IAGI) or the Indonesian Mining Institute (PERHAPI), not just AusIMM/AIG

If you’re reporting for both JORC and KCMI, ensure both CP statements are included.

The one-page test

Before you submit your resource report, pull the resource statement onto a single page. Read it as if you were an investor who only reads one page. Does it answer:

1. How much ore? (tonnes by category)
2. What grade? (grade by category)
3. Above what COG? (cut-off grade stated)
4. As of when? (effective date)
5. By whom? (Competent Person named)
6. On what basis? (reasonable prospects stated)
7. Compared to what? (previous estimate, if any)

If any answer is missing, your statement is non-compliant. Fix it before it goes out the door.